Yenya's World

Sat, 28 Oct 2006

Fedora Core 6

On Tuesday, Fedora Core 6 has been released. Unfortunately, at the same time all Red Hat servers has been DDoSed by someone, but that is another story. I have installed FC6 on my laptop. So far everything works as expected. I have not tried the new Xen GUI management tool or other bells and whistles, but the new fonts (DejaVu, finally!) look nice. I have also taken an opportunity to try Epiphany after some time.

I wrote about Epiphany before. It seems that (together with the epiphany-extensions package) it has become a mature browser, with just few glitches remaining:

Generally speaking, it seems that FC6 is an evolution, not a revolutionary step forward. Which is nice to see.

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Thu, 26 Oct 2006

The Exhaust Pipe

On Friday we have attempted to drive to Tři Studně. However, our car apparently had its own opinion on Friday evening - its exhaust pipe has broken, resulting in audiovisual effects (such as loud noise from the motor and sparks from the pipe being dragged on the surface of the motorway).

It was a bit of luck that the pipe has broken in its rear part, so the car has dragged it behind itself. Should it break in the front part, it would probably have taken the bumper with it. On the other hand, the car broke in an uphill part where there was no emergency stopping lane, but the slow vehicles lane instead. So our emergency triangle has lasted for few minutes only before some truck rode over it. I was then expecting some truck to ride over our car as well. Fortunately, it did not happen.

We were waiting behind the crash barrier, but unfortunately there was a steep slope there, so it was a bit inconvenient. Also Iva has noticed that there was something wrong, so she has cried all the time. Fortunately, after half an hour or so the rescue vehicle came (the price was about 2200 CZK from Devět křížů back to Brno, 2000 of which was covered by insurance - not so bad).

On Sunday, I went to Tři Studně with Iva only - we went there by train, but I took a bicycle with me as well. Guess what has become the best thing Iva likes to play at? She likes to play at repairing the broken exhaust pipe. Oh well.

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Thu, 19 Oct 2006

Bread Maker

Mirka has bought an used bread maker, and we have borrowed it from her. Yesterday we have made bread at work - I think the aroma of bread has been noticable throughout the whole building.

So far it seems it is quite usable, bread is excellent (much better than most kinds of bread which can be bought in shops here). The good thing also is that when we return home after a weekend, it is possible to have a freshly-baked bread on Monday morning, without actually going to the shop. Pavlína wants to do some experiments with baking other things than just bread before we return the bread maker to Mirka.

For those interested, probably the most comprehensive page about bread makers (in Czech) is

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Wed, 18 Oct 2006

Portal Technologies

Yesterday I've attended a new lecture - Portal Technologies in Practice.

The lecture is taught by people from, the biggest Czech portal. The first talk was about their map server. It was a bit non-technical, but interesting nevertheless. The future lectures are promised to be more technical and in-depth.

I've met Vlastimil Pečinka - the present CTO of - there after a quite long time. Many years ago I was a reviewer of his Master thesis, and we have discussed an architecture of IS MU mailserver at that time. His thesis was about the webmail server architecture, and he used it as a basis for implementation of, one of the Czech biggest free-(and non-free-)mails, now owned by

It is always rewarding to see a former student to achieve something great, it gives a feeling like the teaching is not so meaningless ;-)

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Mon, 16 Oct 2006

TMOU 8 Qualification

OK, our team coredump has been qualified for TMOU 8. As always, we had trouble with non-mathematical tasks (especially graphical ones) - #22 and #31 (see the tasks with solutions; in Czech, sorry). The fourth place isn't bad, but the best teams were organizing the qualification this time, so add at least three teams before us to get more real standings.

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Fri, 06 Oct 2006

SIP versus conntrack

Recently I had problems with SIP calls - using tcpdump I have figured out, that the call setup using SIP works fine, but the actual data stream is sent to host, instead to the host from which the remote user is logged in.

After playing with this for a while, I have reported it to the Ekiga mailing list. With Damien Sandras' help, we have found that the SIP Invite packet gets changed somewhere between the sending side and the receiving side - and the change was exactly the reason of malfunction - the IP address was rewritten to the address of host. Some more tests and tcpdump runs later I have figured out that the problem is in our firewall - I have a connection tracking and NAT code compiled in, even though for now I do not use it. But it seems that the SIP helper in the NAT code triggers in even though no NAT is actually set up.

So I have disabled the connection tracking (iptables -t raw -A PREROUTING -j NOTRACK) for now, and SIP calls work again as expected. The further development can be seen in the Netfilter bug #522 (sorry for the misspelled words there :-( ).

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Thu, 05 Oct 2006


I have been to the 29th conference EurOpen.CZ in Mikulov. We (Vlasta and me) have went there by bicycles (fortunately it did not rain when we went there nor during our return trip).

I have enjoyed being there (conferences in the areas of wineyards are always nice :-). The most interesting talk was Zdeněk Říha's talk about electronic passports.

The only bad thing was that on Monday our main server has crashed with an internal error in XFS journal. It is a 2TB+ volume, so xfs_repair took more than six hours to run, and even this was only after we have upgraded it to the latest version - the previous version seemed to loop endlessly in the phase 5. The server has crashed on Monday around 4pm, and with these xfs_repair problems we had the filesystem back around Tuesday 6am, and an hour later the server and the rest of our network was back on-line. That night we have slept for about 4 hour total, with wake-up to check whether the xfs_repair is still running every hour or so.

But despite of these problems, I am glad for serial consoles and remote access, as we can do the fixup remotely from the hotel, without returning to Brno.

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